Starting device for internal combustion engines



A. cALLsEN Dec. 17, 1935.

STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Oct. 3, 1933 2 Sheets-Sheet l Ff .1l

maw/d+@ Dec. 17, 1935. A. cALLsEN STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES 4 Filed Oct. 3, 1933 2 Sheets-Sheet 2 UNITED sTATEs PATENT oFFlcr.

STARTING DEVICE FOR. INTERNAL COMBUSTION ENGINES Albert Callsen, Stuttgart, Germany, assignor to Robert Bosch Aktiengesellschaft, Stuttgart, Germany Application October 3, 1933, Serial No. 692,018 In Germany October 8, 1932 22 Claims; (Cl. 290-38) The present invention relates to a starting On the threaded sleeve 2 is mounted a pinion device for internal combustion engines having a I 3, which in known manner can screw itself pinion which works on a threaded shaft and havalong for engaging in the toothed ring I4 of an ing a friction clutch between the pinion and the engine ily-wheel. Alocking device I5, the pur- 5 driving shaft of .the arrangement. which is pose of which will be hereinafter described, is 5 pressedby the pressure exerted by the quick arranged between the threaded sleeve 2 and the pitch thread of the pinion. The known arrangestarter shaft I (Fig. 4) It consists of a. pin I6, ments of this kind have the great drawback that borne in the sleeve 2 and having two heads I1 the friction clutch is under full driving power and I8. The head I1 projects `radially outwhen, on theengagement of the pinion, its teeth wards from the threaded sleeve 2 whilst the head 1'() encounter the teeth of the toothed ring or crown I8, on the other hand, lies in a recess I9 in the on the flywheel of the engine, and therefore the sleeve. The shaft I has a groove into which teeth, which press on each other with great force, the head I8 of the pin can engage when the pin are moved forcibly past each other .until the is pressed inwards. The pin is pressed out- 15.-v pinion teeth come into register with the tooth wards by a spring 2I located between the sleeve L., gaps of the iiywneel ring. In these circumand the head I1. The pin is forced inwards by stances, the teeth of the pinion and the toothed the pinion I3; which for this purpose has an anring of the flywheel are very rapidly worn out, nular extension 22, the inner wall of which first or their faces so damaged that engagement is contracts from the edge and then again enlarges 20 impossible when tooth meets tooth. -These drawinto the form of a channel. The pin in the 2U backs are avoided according to the invention, by sleeve, the groove 20 in the shaft I, and the conthe friction clutch being soformed, that on the tracted portion in the extension of the pinion enga-gement on the pinion, it'can transmit only are so arranged that they come to lie in one I a small torque, but on the starting of the engine plane when the pinion is in contact with the A... a great torque. crown or toothed ring I4 of the flywheel. Y

Two examples of construction of the invention The shaft I has a iiange or collar 39 between are shown in the accompanying drawings, in its bearing on the side where the pinion is sit- .Whichzuated and the threaded sleeve 2. This i12-nge 0I' Figure 1 is a longitudinal sectional view of an collar has projections 40 on the side facing the electric starter in the position of repose. sleeve 20, which engage in corresponding re- 30 Figure 2 is a similar view showing the starter cesses 4I in the front end of the threaded sleeve. Lill its WOrkng pOSitiOn. That part of the shaft I on which the arma- Figure 3 is a diagram of the electrical connecture 23 and the commutator 24 of the starter are tions of thestarter` mounted has a bore 25, which extends from the Figure 4 iS a fragmentary View. end of the shaft up to about the middle of the 35 Figure 5 is a sectional view of a second form clutch. In the bore is located a rod 26, which at of construction. its iner end carries a pin 21 which passes through Figure 6 is a section on the line 6 6 of Figslots 28 inthe shaft I and engages in a groove ure 5. 29 on the inner end of the threaded sleeve 2. On

.40 On the starter shaft I of the electric starter the end of the rod 26, projecting from the shaft o illustrated is mounted a threaded sleeve 2, which I are secured an iron core 30 and a current is freely revoluble and axially displaoeable relabridge 3l. The iron corel lies within a magnet tive to the shaft I, but can be connected with it coil 32. A compression spring 34 is arranged beby means of a friction clutch 3. The part of the tween the end of the rod and the casing 33. Two clutch connected with the shaft I consists of a' contacts 35 are situated opposite the current 45 bell 4 keyed on the shaft and a number of -fricbridge 3l, and in the manner shown in the wirtion diSCS 5 engaging in grooves 6 in the wall of ing diagram (Figure 3) lie in the circuit of the the bell, and of an annular disc 1 `which is sestarter. cured to the edge of the bell. The other part of The 4magnet coil is connected by a Cable 35 the clutch is formed by friction discs 8 located in with the spring contact 31 of a switch 38, which 50 grooves 9 in the threaded Sleeve 2 and by a flange is so arranged fm the casing of the starter that l0 of the threaded sleeve which lies between the the switch is closed by the pinion when this is in annular disc 1 and the friction discs 5, 8. vThe full engagement, but on the other hand is open friction discs bear against a pressure plate II, when the pinion is out of engagement with the a5A which in its turn bears on a sprngy disc I2. crown of the ywheel M 55 In the wiring diagram, 42 is a battery to which the armature 23 and the held-winding 43 are connected in series. 44 is the main switch of the starter circuit, and 45 a` series resistance which is inserted in the circuit between the switch and the starter winding. At the ends of the series resistance, leads branch off to the contacts 35, which can be, connected together by the current bridge 3I.v Further, a cable 46 is connected to the battery and leads to the switch 38, which is connected by the cable 36 with the 'magnet coil 32.

In Figure 1 the starter is shown in the position of repose. Inorder to put the starter into operation, the switch 44 is closed. A weak current'due to the series resistance then flows at first from the battery through the starter, and causes the armature 23 and its shaft I to rotate at a relatively moderate speed. The threaded sleeve 2 is connected during this operation `with the shaft I through the friction-clutch consisting of the bell 4, disc l, and ange I0 and compressed by the pressure of the spring 34, and therefore rotates with the shaft I. At the same time the pinion I3 owing to its inertia screws itself along the sleeve 2 towards the flywheel crown I4. If now the teeth of the pinionencounter those of the crown of the flywheel, the pinion is thereby hindered both in its rotation with the sleeve 2 and also in further axial movement. 'Ihe sleeve now tends to screw itself in the pinion, which tends to remainstationary away from the crown of the flywheel against pressure of the spring 34, andthereby reduces the coupling pressure of the discs land I0. The clutch therefore begins to slip, and so long as the pinion is hel" fast, transmits only a quite small torque frothe shaft I to the sleeve 2. Owing to the torque transmitted being small, the pressure with which the pinion is pressed against the crown of the -flywheel, and the friction between the pinion and the crown of the flywheel, is also small, so that the pinion can be rotated by the continuous slight drive of the slipping clutch, until the vteeth of the pinion are in register with the tooth gaps of the flywheel. So long as the clutch is slipping the sleeve 2 rotates relative to the shaft I and is therefore pressed back by the projections 48 on the shaft I by a small amount. By this means the pinion is alsomomentarily lifted from the crown of the fiywheel or at least its seat on the ywhcel loosened and can rotate withl the sleeve and correctly engage.

en tooth meets tooth, it may happen that th -sleeve 2 owing to its inertia would tend to be screwedback in the'pinion to such an extent that its flange I0 would come against the friction discs 5, 8 and drive them. .'I'he pin I6 in the sleeve 2 is provided in order to avoid this. It is forced by the extension 22 on thelpinion into the ygroove 28 in the shaft precisely when the pinion comes in contactv with the iiywheel crown (Fig. 4).- The sleeve 2 isso connected with the shaft I by the pin I6 that it can move axially only to such an extent as the head I8 has play in the groove. This amount is smaller than the distance of the ange Ill from the friction discs 5.

When the -pinion is fully in mesh A(Fig. 2), it closes the switch 38, which connects the magnet coil 32 with the battery.- -The magnet coil attracts the core 30 with the rod 25 and draws the sleeve 2, connected with the rod through the pin 2`I,-towardsthe left (Fig. 2) away from the flywheel. the pin I5 having been previously released from the groove 20 by movement ofthe pinion fully into mesh with the nywheel crown. At the same time the flange I I) on the sleeve 2 comes to bear on the friction discs 5, 8 and actuates them. Further, the series resistance is short-circuited so that the starter is directly at the full 5 voltage of the battery and works at full power. The clutching pressure of the frictionv discs 5, 8 that is exerted by the sleeve 2 increases according to the torque transmitted. As soon as the engine is started and running under its own power, the w pinion screws itself out of the toothing on the flywheel crown and simultaneously the sleeve 2 is again pushed by the spring 34 towards the nywheel, so that the flange I0 again bears on the disc 1. 15

In Figures 5 and 6A a second form of construction is shown, in which the clutch for the starting of the engine is cut in by mechanical means instead of by a magnet coil. For this purpose a spring 41 is secured on the threaded sleeve 2 and 20 bears on the inner wall or face of the bell 4. This arrangement works in the following way: When ,the starter is switched on by means of the switch 44, the armature shaft rotates and drives the sleeve 2 through the bell 4 and the spring, where- 25 by the pinion travels towards the crown of the flywheel. When tooth meets tooth, the sleeve is secured against axial displacement for cutting in,

the clutch 5, 8 by the pin I6 depressedv into the groove 2l) of the shaft I by the extension 22 f 30 the pinion, so that only a torque corresponding to the friction between the spring 41 and the bell 4 i's transmitted to the sleeve 2 and the pinion I3 from the shaft I. The axial pressure with which the pinion is pressed against the crown 0f 35 the flywheel and the friction between the pinion f 'and the crown of the flywheel is small, because the torque which is transmitted by the spring is slight. When the pinion is fully ,-in mesh with the crown on the flywheel, the pin I6 is withdrawn 40 from the groove 20 by the spring 2|, and thus the sleeve 2 unlocked, so that it can screw itself towards the discs 5, 8 until the flange III bears Von these discs, and thereby the clutch is cut in for-the speeding up of the sleeve 2 and thus the' 45 engine.

The advantage of the invention lies in the fact .that on the engagement of the pinion a clutch iseffective which can transmit only a small torque. By this means the shock when tooth 50 meets tooth and the friction on the teeth of the pinion and the flywheel is so weak that damage to the pinion or flywheel crown and a seizing ot the pinion is avoided. Y

I declare that what I claim is:

1. A starting device for internal combustion engines, 'comprising a driving shaft, a pinion adapted for automatic axial displacement rela-V tively to said shaft towards and away from a ilywheel crown, a friction clutch between the driv- 0o ing shaft and theipinion and means movable in one direction for lightly engaging the said clutchl during movement of the pinion 'into mesh ,with the iiywheel crown and movable in the opposite I direction for heavily engaging the clutch when if the pinion is in mesh with the crown for starting up the engine. I

2. A starting device for internal combustion engines, comprising a driving shaft, a pinion movement of the pinion into mesh withfthe flywheel crown and electromagnet means for heavily clutching the pinion with the shaft before the actual starting up of the engine.

3. A starting device for internal combustion engines, comprising a driving shaft, a pinion adapted for automatic axial displacement relatively to said shaft towards and away from a flywheel crown, resilient means for frictionally transmitting a relatively light torque from the driving shaft to the pinion during its movement into mesh with the flywheel crown and electromagnetic means for subsequently transmitting a heavier torque to the pinion when in mesh with the flywheel crown for starting up the engine.

4. A starting device for inter'nal combustion engines, comprising a driving shaft, a pinion adapted for .automatic axial displacement relatively to said shaft towards and away from allywheel crown, a friction clutch between the driving shaft and the pinion, resilient means for lightly engaging the said clutch during movement of the pinion into engagement with the flywheel, crown and electromagnetic means for heavily engaging the clutch when Athe pinion is in mesh with the crown for starting upthe engine.

5. A starting device for internal combustion engines, comprising a driving shaft, a pinion adapted for automatic axial displacement relatively to said shaft towards and away from a flywheel crown, a friction clutch between the driving shaft and the pinion, means, governed by the axial position of the pinion, movable in one direction for lightly engaging the saidclutch during movement of the pinion into engagement with the flywheel crown and movable in the opposite direction for heavily engaging the clutch when the pinion is in mesh with the crown for starting up the engine.

6. A starting device for internal combustion engines, comprising a driving shaft, a pinion adapted for automatic axial' displacement relatively to said shaft towards and away from a flywheel crown, a friction clutch between the driving shaft and the pinion, and a screwable and axially displaceable pressure member' adapted to govern the engagement of the clutch, said pressure member being adapted to exert pressure in one direction to cause a light engagement of the clutch during movement of the pinion into engagement with the flywheel crown and to exert pressure in the opposite direction for heavily engaging the clutch when the pinion is in mesh with the crown for starting up the, engine.

.7. A starting device for internal combustion engines, comprising a drivingV shaft, a pinion adapted for automatic axial displacement relatively to said shaft towards and away from a flywheel crown, a friction clutch between the driving shaft and the pinion, and a screwable and axially displaceable pressure member adapted to govern the engagement of the clutch, said pressure member being adapted to exert pressure vin one direction to cause a light engagement of the clutch during movement of the pinion into engagement with the flywheel crown and to exert pressure in the opposite direction for heavily engaging the clutch when the pinion is in mesh with the crown`4 for starting up the engine, and electromagnetic means for altering the direction of. pressure of said pressure member for heavy engagement of the clutch.

8. A starting device for internal combustion engines comprising a driving shaft, a pinion adapted for automatic axial displacement relatively to said shaft towards and away from a fly for wheel crown, a friction clutch between the driving shaft and the pinion; and a screwable and axially displaceable pressure member adapted to govern the engagement of the clutch, said pressure member being adapted to exert pressure in one direction to cause a light engagement of the clutch during movement of the pinion into engagement with the fly wheel crown and to exert pressure in the opposite direction for heavily engaging the clutch when the pinion is in mesh with the crown for starting up the engine and electromagnetic means operable in dependence upon the position of the pinion for altering the direction of pressure of said pressure member for heavy engagement of the clutch.

9. A starting device for internal combustion engines comprising a shaft, a pinion adapted for automatic axial displacement relatively to said shaft towards and away from a fly wheel crown, a friction clutch between the driving shaft and the pinion, and a screwable and axially displaceable pressure member adapted to govern the engagement of the clutch, said pressure member being adaptedv to exert pressure in one direction to cause a light engagement of the clutch during movement of the pinion into engagement with the fly wheel crown land to exert pressure in the opposite direction for heavily engaging the clutch when the pinion is in mesh with the crown for starting up the engine, electromagnetic means for altering the direction of pressure of said pressure member for heavy engagement of the clutch and a switch in the circuit of said electromagnetic means adapted to be closed as vvthe pinion moves into mesh with the fly wheel crown.

10. A starting device for internal combustion engines comprising a driving shaft, a sleeve rotatable and axially displaceable on said driving shaft and ,having at least one screw thread on its outer surface, a pinion on said driving shaft having at least one screw thread on its inner surface to cause axial displacement of the pinion relatively to the shaft towards and away from a fly wheel crown, a friction clutch between the driving shaft and the sleeve including at least one member connected to the driving shaft and at least one member connected to the sleeve, resilient means for lightly engaging the clutch the fly wheel crown, the said sleeve being adapted for axial displacementv in opposition to said re siliient means to cause heavy engagement of the clutch when the pinion is in mesh with the fly wheel crown for starting up the engine.

1l. A starting device for internal combustion engines comprising a driving shaft, a sleeve rotatable and axially displaceable on'said driving shaft and having at least one screw thread on its outer surface, a pinion on said driving shaft having at least one screw thread on its innersurface to cause axial displacement of the pinion relatively to the shaft towards and away from a fly wheel crown, a friction clutch between the driving shaft and the sleeve including at least one member connected to the driving shaft and at least one member connected to the sleeve, resilient means for lightly engaging the clutch during movement of the pinion into mesh with the y wheel crown, the said sleeve being adapted xial displacement in opposition to said resilient means to cause heavy engagement of the clutch when the pinion is in mesh with the fly wheel crown for startingup the engine and locking means dependent upon the position of the rpinion for limiting the axial displacement of the engines comprising a driving shaft, a sleeve rotatable and axially displaceable on said driving shaft and having at least one screw thread on its outer surface, a pinion on said driving shaft having at least one screw thread on its inner surface to cause axial displacement of the pinion relatively to the shaft towards and away from a ily wheel crown, a friction clutch between the driving shaft and the sleeve including at least one member connected to the driving shaft and at least one member connected to the sleeve, resilient means for lightly engaging the clutch during movement of the pinion into mesh with the iiy wheel crown, the said sleeve being adapted for axial displacement in opposition to said resilient means to cause heavy engagement of the clutch when the pinion is in mesh with the ily-wheel crown for starting up the engine and a pin passing transversely throughthe threaded sleeve and through the driving shaft for interconnecting these two members.

13.' A start-ing device for internal combustion engines comprising a driving shaft, a pinion adapted for automatic axial displacement relatively to said shaft towards and awayfrom a ily wheel crown, means for transmitting a relatively small torque from the driving shaft to the pinion bduring movement of the pinion into mesh with the y wheel crown, a friction clutch for transmitting a. relatively heavy torque from the shaft to the pinion when this is in mesh with the fly wheel crown and mechanical means for.

15. A starting device for internal combustion engines comprising a driving shaft, a pinion adapted for automatic axial 'displacement relatively to said shaft towards and away from a fly wheel crown, a continuously operating friction clutch for the transmission of a relatively v small torque from the driving-shaft to the pinion and a friction clutch adapted to come into operation and to transmit a relatively heavy torque from the driving shaft to the pinion when the pinion is in mesh with the fly wheel crown, the said continuously operating friction clutch being .adapted to cause engagement of said clutch for transmitting the heavy torque when the pinion is in mesh with the flywheel crown.

16. A starting device for internal combustion engines comprising a driving shaft, a rotatable and axially displaceable sieeve on said shaft having at least one screw thread on its outer surface, a pinion on said sleeve having at least one thread on its inner surface to cause axial displacement of the pinion relatively to the shaft towards and away from a fly wheel crown, a disengageable friction clutch between the driving shaft and the sleeve adapted to be engaged by the thrust of the sleeve whenk the pinion is in mesh with the y wheel crown, and a continuously operating vfriction clutch adapted continuously to transmit a 'light torque from the driving shaft to the sleeve to cause a relatively 5 gentle engagement of the pinion into mesh with the ily wheel crown and also to set up an initial thrust between the sleeve and the clutch after the pinion has meshed with the fly wheel crown.

17. A starting device for internal combustion engines comprising a. driving shaft, a pinion adapted for automatic axial displacement relatively to said shaft towards and away from a ily wheel crown, an electric motor mounted on said shaft, resilient means for lightly clutching the pinion with the driving shaft during movement of the pinion into mesh with the y wheel crown, electromagnetic means for heavily clutching the pinion with the driving shaft when the pinion is in mesh with] the y wheel crown, and means for, increasing vthe power output 0f said motor when the pinion is in mesh with the fly wheel crown. Y

18. A starting device for internal combustion engines comprising a driving shaft, means v mounted on said shaft for rotary and axial movement relative thereto, means for clutching said means to said shaft, a pinion driven by and mounted on said.firstmentioned means for automatic displacement relative thereto towards and away from a flywheel crown, said rst-mentioned means causing a light engagement of said clutching means during movement of the pinion into mesh with the flywheel crown and beingA axially movable to cause a heavy engagement of said clutching means when the pinion is in mesh with the crown for starting up the engine.

19. A starting device as in claim 18 including resilient means for urging said first-mentioned means in one direction. axially of said shaft, and .w electromagnetic means for initiating movement in the opposite direction.

20. A starting device for internal combustion engines comprising a driving shaft, a sleeve mounted on said shaft for rotary and vaxial 4,-, movement relative thereto, means including two sets of clutch surfaces for clutching said sleeve to said shaft, a pinion driven by and mounted on said sleeve for automatic displacement relative thereto toward and away from a flywheel crown, one set of said clutch surfaces being in engage- -ment during movement of said pinion into mesh with the flywheel crown to transmit a relatively light torque from the driving shaft to said pinion during said movement, said' sleeve being axially 55 movable to cause engagement of the other clutch surfaces to transmit a heavier torque from the driving shaft to the pinion when said pinion is in mesh with the flywheel crown.

21. A starting device as in claim 20 including 60 resilient means urging said sleeve to cause light engagement of one set of clutch surfaces and means controlled by said pinion for operating said sleeve to cause engagement of said other clutch surfaces.

22. A starting device as in claim 20r including resilient means urging said sleeve to cause light engagement of one` set of clutch surfaces, and electromagnetic means to initiate engagement of the other clutch surfaces, the reaction of the pinion when in mesh with the flywheel crown operating said sleeve to cause a heavy engagement of said other clutch surfaces.

ALBERT CALLSEN. 

